i don't know what titanfall 2 is or what's going on around, but this is a bull explanation whether or not the exploit is real. modern filesystems used by systems such as NTFS & EXT4 don't overwrite files like this. whatever is happening, the whole paragraph in the image is wrong
if you think this is a confirmation that there is a working exploit, you need reading comprehension classes https://mobile.twitter.com/Respawn/status/1435740468327899139
if the explanation is supposed to mean a buffer overrun in RAM instead that's a little more plausible, but modern systems still have enough protections against that affecting the rest of your computer and i honestly doubt you could effectively put an RCE payload in an username